A variety of so-called low-alloy and high-alloy cast iron compositions have heretofore been used or proposed for use in the fabrication of components subject to severe abrasion during service, such as for example, for use in the fabrication of pump components for handling sand and abrasive slurries, chute liners, sand and shot blast equipment and cast liners in ore grinding mills and the like. Typical of such alloys are those described in U.S. Pat. No. 2,662,011 and U.S. Pat. No. 3,410,682, comprising high chromium white cast irons containing nickel and molybdenum as essential alloying constituents. It is conventional practice when casting components from such white cast irons to subject them to further heat treatments to enhance their hardness and wear resistance over that provided in the as-cast condition. In many instances, castings composed of prior art type white cast iron alloys having relatively thick sections, or sections varying in thickness cannot be satisfactorily heat treated to achieve optimum properties due to the susceptibility of such castings to damage or fracture during the heat treatment cycle.
The present invention provides a high-alloy nickel-free high chromium white cast iron which is composed of a novel combination of alloying constituents present in carefully controlled amounts such that the iron is possessed of good toughness and abrasion resistance in the as-cast condition. The mechanical properties of cast components can be further enhanced, even for castings having configurations which cannot ordinarily be heat treated in accordance with prior art practices, by subjecting them to a refrigeration hardening treatment, whereby further beneficial transformations in the microstructure of the alloy are effected.